Burner control



sept 1932 R. J. ElsEMAN 1,876,281

BURNER cou'rRoL Filed Nov. 17, .1930 2 Sheets-Sheet 1 )van fha-m. /7 l,

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4m? @ITW 'Patented Sept. 6, 19132' UNITED STATES PATENt ori-lcs ROBERTJ. EISEHAN, OF WILLOUGHBY, OHIO, ABSIGNOB TO THE K-W. IGNITION COB-PORATION, OF CLEVELAND, OHIO, A. CORPORATION 0F OHIO mmm commer.

Application Med November 17, 1930. Serial No. 490,158.

This invention relates to improvements in burner controls, that is tosay electric systems for automatically regulati the o eration of aburner so as to provide eat su cient to maintain the temperature of aroom or series of rooms at a given point, within relatively closelimits.

It is of considerable importance, particularly where certain fuels areemployed, to guard against the discharge of fuel into the burner when nomeans for igniting the same is available, and it is also important toguard against employing too great a degree of heat in bringing thetemperature u to the predetermined level after the rooms ave been cooleddown considerably.

One object of the invention therefore is the provision of a safetyswitch for opening up the operating circuit when for any reason thefurnace fails to heat up after the fuel is turned on in response to acall for heat from the room thermostat. Such a condition might arise forinstance where there was a failure in the ignition of an oil burner.

Another object is the provision of means to maintain the operatingcircuit open or at safety until manually closed, thus insuring that thedifculty will be given atten-l tion and correction.

Still another object of the invention is the provision of means foroperating the safety switch electrically, and

'A further object is the provision of an additional safety circuit orline through a room thermostat and a thermostat associated with theheating unit, these latter thermostats being arranged in arallel so thatif the temperature both in t e room and in the furnace should rise abovepredetermined points, the operating circuit wouldbe put -on safety.

Other ob'ects and features of novelty will appear as I proceed with thedescriptlon of those embodiments of the invention which, for thepurposes of the present application, I have illustrated in theaccompanying drawings, in which igure 1 is a diagram of electricalclrcults emfpodying the invention, the burner being of Fig. 4 a furthersafety provision 1n accordance with which the operatin circuit goes onsafety in the event that oth the room and the furnace temperatures riseabove predetermined points.

In the drawings I have illustrated the invention as applied to an oilburner control system, but it should be understood that it is uallyadaptable to controls for systems in w ich other fuels are employed, thenecessary changes beingI readily made by one skilled in the art.

In the drawings a pair of alternating current service wires areindicatedat 10 and 11. An electric motor for feeding carbureted oil tothe burner is indicated at 12, and the magnet of an electricallyoperated oil valve at 13. The sparking points of the ignition means areshown at 14, being in circuit with the secondary coil of a transformer15.

Referring now particularly to Figs. 1, 2 and 3, 16 is the primary coilof a transformer employed for stepping down the voltage from the 110volt line to 20 volts or thereabouts, as is most suitable for thecontrol circuits. One leg of the coil 16 is connected with line wire 10by a conductor 17. The other leg is connected through conductor 18 withthe fixed end of a iexible switch arm 19 carrying a contact 20 thatengages normally with the ixed contact 21 which is connected by aconductor 22 with line wire 11.

The operating circuit runs from line wire 10 through conductors 23 and24. Motor 12 and fuel valve magnet 13 are arranged in parallel betweenconductor 24 and a conductor 25 which is connected to the fixedextremity of an arm 26 of thermostatic metal,

constituting one element of the operating switch. Upon this arm ismounted a contact 27 that is adapted to en age a contact 28 mounted onAanother flexi le switch arm 29 that is electrically joined to the baseor fixed extremity of the arm 19.- The thermostatic arm 26 also carriesa projecting rod or ram 30 that is adapted to engage arm 19 and swing itso as to separate contacts 20 and 21, as indicated in Fig. 3. Theconductor 24 is connected with a contact 31 against which rests normallyan armature 32 that is pivotally mounted at 33 and there connected witha conductor 34 which runs to one leg of the primary coil of ignitiontransformer 15.

In the control circuit there are incorporated contacts 35 and 36 of aroom thermostat and contacts 38 and 39 of a heat control thermostat 40,the latter thermostat being positioned in or upon the furnace and soarranged that its contacts close shortly after the burner ignites. Thethermostatic switch v 37 works in the reverse manner, that is to sayitscontacts 35 and 36 come together when the room temperature fallsbelow a predetermined point, and theg open again when the temperaturerises a egree or two above that point. v

The contact 36 is connected by aconductor 41 with one leg of a secondarycoil 42 of the step-down transformer, the other leg being connected by aconductor 43 with contact 38. Contact 35 is connected-by va conductor 44with a rela coil 45, and thence the circuit goes throng a conductor 46to a second relay coil 47 and from there b way of a conductor 48 tocontact point 39. Instead of relay coils and 47 I may em loy asin lecoil with two armatures, and in act I pre er to do so, but for the sakeof clearns and simplicit in the diagrams I have shown se arate co' Thearmature 32 is adap to be raised by the energization of coil 47, asindicated in Fig. 2. Coil 45 controls an armature 49 which normallyrests upon a contact 50 that is connected b a conductor 51 with aheating coil 52, from t e opposite end of which a conductor 53 extendsto conductor 43. From the pivot point 54 of armature 49 a shortconductor 55 leads to conductor 44. The armature 49 is normally urgedtoward the position illustrated in Fig. 1, as by a coil spring 56. Onthe rear end of armature 49 ythere is a depending finger 57 which, whenthe coil 45 is energized, may take a position behind the flexible armv26of the operating switchas indicated in Fig.' 2. When, as indicated inFig. 3, the ram 30 pushes the switch arm 19 to the left to separatecontacts 20 and 21 the upper end of that arm travels over a cam shapedsurface on a latch 58 until it snaps into a recess in the latter. Thelatch therefore holds the contact 20 away from contact 21 until thelatch is manually released.

Referring to the operation of the system illustrated in Figs. 1, 2 and3, the condition of the system when the room temperature is at or abovethe predetermined desired point,

is shown in Fig. 1. At this time the valve 1,sve,2s1 I m et 13 isdeenergized, the motor 12 is idle an there is'no current through thetransformer-15. Now, when the temperature of the room falls somewhat thecontact points 35 and 36 of the room thermostat 37 will come together. Acircuit will thereb be set up through the transformer secon ary coil 42and heating coil 52. This circuit may be traced from coil 42 throughconductors 43 and 53 to coil 52, and thence by way of conductcr 51,contact 50, armature 49, conductors 55 'and 44 to contacts 35 and 36 ofthe room thermostat, and by conductor 41 back to coil 42. The coil 52then heats up and the thermostatic arm 26 being positioned adjacent thatcoil, warps away from the position of Fig. 1 to that of Fig. 2, causingthe contact 27 to engage the contact 28, thus closin the operatingswitch. 110 volt current now ows through the valve magnet 13, motor 12and ignition coil 15. The circuit for the motor and valve may be tracedfrom line wire 10 through conductors 23 and 24, through the motor andvalve magnet in parallel, thence by way of conductor 25 to thermostaticswitch arm 26, contacts 27 and 28, switch arms 29 and 19, contacts 20and 21 and conductor 22 to line wire 11. At the same time the ignitiontransformer 15 is energized, the circuit including the conductors 23 and24 leading from line wire 10 through contact 31, armature 32, pivot marycoll of e transformer 15 to conductor 25, and thence to line wire 11through the same path as in the case of the motor and valve magnetcircuit. Fuel is thereb fed to the burner and ignited by the sparkstween points 14.

The heat control thermostat 40 then begins to warm up and in a shorttime the contacts 38 and 39 thereof close, completing a circuit fromtransformer coil 42 through conductor 43, contacts 38 and 39, conductor48, relay coil 47 conductor 46, relay coil 45, conductor 44, contacts 35and 36 and conductor 41 back to cil 42. The armatures 32 and 49 arethereby swung upwardly on their pivots to the positionsv illustrated inFig. 2. The circuit through the transformer 15 is therefore broken andignition ceases. The circuit through heating coil 52 is also broken, butat the same time the linger 57 is projected downint 33 conductor 34, thepriwrdly behind the thermmic switch am any time that when the roomthermostat is calling for heat and the burner is in operation, the fireshould go out for any reason whatever, the heat control thermostat 40would be affected immediately, the contacts 38 and 39 would open,opening the circuit through relay coils 45 and 47 and permittingarmatures 32 and 49 to fall back into the positions of Fig. 1. Thesystem would then be reset for operation precisely as it was at thebeginning of the cycle, that is to say the thermostatic switch arm 26would be in the position of Fig. 1, having been released by the finger57, the heating coil 52 would be energized, the ingition circuit wouldagain funetion, and when the thermostatic arm 26 became warm enough itwould warp into position to close contacts 27 and 28, whereupon themotor and fuel valve magnet would again start functioning.

If there should. be a momentary failure of current in the line wires 10and 11 while the burner was in operation, the armatures 32 and 49 wouldfall and then swing up again. Thermostatic arm 26 would straighten upwhen the current went off and when it came ,on again finger 57 woulddescend in frontof arm 26 instead of behind it, thus latching that armin the retracted position. 'The operating circuit would then be deprivedof current until such time as the furnace cooled down sufficiently toopen contacts 38 and 39 of thermostat 40, whereupon the armatures 32 and49 would again fall, and all parts would be in position to begin theregular cycle of movements through which they pass to start the burner.

Fig. 3 illustrates what would occur in my system should the heat controlthermostat 40 fail to function when a fire is started in the burner.Under such conditions the relay coils 45 and 47 would not be energizedand the armature 49 would not rise to open the circuit through heatingcoil 52. The thermostatic arm 26 would then not s top warping when thecontacts 27 and 28 engaged, but would continue until the ram 30 carriedby the arm 26 pushed against switch arm 19, separating contacts 20 and21 and driving the upper end of that arm past the cam surface of springlatch 58 into the notch of that latch. As the current for the motor 12,fuel valve magnet 13 and ignition coil 15 must pass through contacts 20and 21, the burner would then cease to operate andthe switch arml19,which I have herein termed the safety switch, would be latched in openposition and so held until manually released. The actuation of thesafety switch is an indication that something in the system is out oforder, and hence calls for a careful inspection and a correction of thedifficulty.

If the contacts 38 and 39 of thermostat 40 should stick in the closedposition instead of in the open position, it would result merely in afailure of the system to operate, because when the contacts `of the roomthermostat would close the relay coils 45 and 47 would immediatelybecome energized and would attract their armatures with the result thatthe circuit through heating coil 52 would be opened and the thermostaticoperating switch 26 would not close.

Attention is called to the fact that ifthe system should functionwrongly in any respect so as either not to energize coil 52 or not toterminate the energization of the coil at the proper time, no harm canresult. In the first case the operating 4circuit would merely remainopen. In the second case the system would go on safety, and all currentthrough it would be interrupted, that is t0 say not only the 110 voltcurrent through the lnotor, fuel valve magnet and ignition coil, butalso the current through the primary coil 16 of the step-downtransformer which furnishes low voltage current to the circuitsincluding the heating coil 52.

In Fig. 4 I have illustrated a modification of the system embodying anelectrical operation of the safety switch rather than an` operationdirectly by the warping of the thermostatic switch arm.` In otherrespects the system is the same as that previously described. In thisform of the invention a conductor 60 extends from one leg of the primarycoil 16 of the step-down transformer to a contact 61 which is normallyengaged by an armature 62 that constitutes the movable element of thesafety switch. The end of this armature `works against a cam surface ona latch 63 which corresponds in design and function with the latch 58 ofthe above described form of the invention. From the pivoted end of thisarmature a conductor 64 extendsqto line wire l1. To conductor 60 thereis joined a conductor 65 which divides into two conductors 66 and 67leading to the two coils of a balanced relay 68, one coil of which isattached through conductor 69 with contact 21, and the other coil ofwhich is connected through conductor 70 with the fixed ends of switcharms 19 and 29.

Current for the operating circuit passes from line wire 10 throughconductors 23, 24, motor 12 and fuel valve magnet 13 in parallel,conductor 25, thermostatic switch arm 26 and contacts 27, 28 (whenclosed by the action of the control circuit working through heatingcoily 52) to switch arm 29. From switch arm 29 the current passes inparallel through the two coils of relay 68, in one case throughconductor 70, the lower relay coil line wire 1l. When both coils arethus ener-- gized their effect is neutralized and consequently thearmature 62 is not attracted.

The operation is like that of the first described form of theinventionexce t that ifthe heat control thermostat 40 Y ails to function,resulting in the continued flow yof current through heating coil 52, ram30 pushes against switch larm 19 to efpen contacts 20 and 21. Thereuponall o the operating current flows through the lower. coil lonly of relay68, throwing the relay out of balance so as to attract varmature 62 andbreak not only the operating circuit, but also the circuit throughtransformer ,coil 16 which furnishes current for the control circuits.The' armature 62 is raised until its end springs into the socket oflatch 63 and the system is thereby held on safety until the latch ismanually released. The ordinary operation of the system is recisely thesame as in the case ofl the first escribed the invention.

In the process of bringin the temperature of a room up from a low evelthe furnace may get too hot. The system illustrated in Fig. 5 isdesigned to prevent such a condition. In this system I employ athermostat associated with the heating unit. This thermostat may belocated in the chimney or smoke stack, or it may be associated with theboiler or otherwise positioned to be affected directly by the operationof the furnace. It has two sets of contact-,s 71, 72 and 73, 74 whichare normally closed, but which open when the heat that is permitted tocome in contact with the thermostat exceeds a predetermined degree thatis considered safe. The contacts 73 and 74' are interposed between theends of conductor 23, which is a part of the 110 volt operating circuit.When thev temperature of the room or house has been permitted to fallfar below the temperature for which the room thermostat is set, and thesystem is then permitted again to function normally, the furnace maybecome heated highly enough to open contacts 73 and 74 more than once inthe process of bringing the house up to the desired temperature. Eachtime this occurs the operation of the burner merely ceases temporarily,owing to the fact that the system goes on safety position, and remainsthere until the safety latch is manually released. It occurs in thisway. When the contacts 73 and 74 are disengaged, the circuit through themotor 12 and valve 13 is broken. The furnace then begins to cool, andthermostatic switch 38, 39 opens, permitting armature 49 to return tothe position indicated in Fig. 5. Current form ofv In my system asshownin thisgure there is provided a further safety control the operation ofwhich the system will go on safet should the temperature of the room exthe predetermined desired level and the temperature inthe furnace exceedthe predetermined safe level both at the same time. In this way, if thecontacts 71 and 72 should fail to open for any reason then, as soon asthe room tem rature reached the predetermined level, t e system would goon safety and such a condition would constitute warning that somethingin the system was out of order and therepair of the ther-v mostat 90would naturally follow, I will now ex lain how this condition comesabout.

, n Fig. 5 the room thermostat 75 also carries two sets of contacts, themovable elements of which are to move together, an only one of whichtherefore need be made of thermostatic metal. These pairs of contactsare numbered 76, 77 and 78, 79 respectvel in the drawings. Contact 76 isconn to the conductor 44 of the control circuit, while'contact 77 iscon-` nected through a conductor 80 with one leg of the secondary coil42 of the step-down transformer. The other leg of that coil is connectedthrough a conductor 81 and va. conductor 43 with lthe contact 38 of theheat control thermostat 40. One end of the heating coil 52 is connectedthro h a conductor 82 and conductor 81 to the er le of coil 42. whenvthe contacts 76, V77 of t e room thermostat close therefore in theordinary functioning of thatthermostat, current may flow from the coil42 through conductor 80, contacts 77, 76, conductors 44, 55, pivot point54, armature 49, contact 50, conductor 51, heating coil 52, andconductors 82 and 81 back to coil 42. Coil 52 is thereby energized towarp thermostatic switch arm 26 and close the operating circuit as inthe previously described forms of the. invention. Shortly thereafter thecontacts 38 and 39 of thermostat 40 close also, and current flows fromVcoil 42 through conductor 80, contacts 77 76, conductor 44, relay coil45, conductor 46, relay coil 47, conductor 48, contacts 38 and 39 andconductors 43 and 81 back to the coil. The circuit through heating coil52 is thereby opened and the finger 57 is caused to descend referablyconnected behind the war ed arm 26 in a manner similar to that indicatedin Fig. 2.

Contacts 7 2 and 78 are joined by a conductor 83, while contacts 71 and79 are joined by a conductor 84. Conductor y83 is connected by aconductor 85 with fixed contact 21, while conductor 84 is connected by aconductor 86 with the fixed end of switch arm 29. The latter arm is alsoconnected, as in Fig. 4, with the lower coil of relay 68 by a conductor70. In this form of the invention the operating circuit takes thefollowing path: From line wire 10 through conductor 23, contacts 73, 74,conductors 23, 24, motor 12 and valve magnet 13 (also contact 31,armature 32, conductor 34, ignition coil 15) conductor 25, contacts 27,28 (then closed) to switch arm 29. From this point the current throughrelay 68 divides, substantially half of it going directly throughconductor 70 and the lower coil of the relay, while the balance takesthe path through conductor 86, conductor 84, one or the other or bothpairs of contacts 71, 72 and 78, 79, conductors 83 and 85, contacts 21,20 and conductor 69 through the upper coil of the relay. Hence thearmature 62 is not attracted. If, however, both sets of contacts 71, 72and 78, 79 should be open at the same time, then all of the operatingcurrent would pass through the lower coil or relay 68 and the armature62 would be' attracted and drawn into engagement with the latch 63, thusputtin the system on safety lhile in the foregoing description and inthe accompanying drawings-I have disclosed certain particularembodiments of the invention more or less in detail, I desire it to beunderstood that such detail disclosure has been resorted to primarilyfor the purpose of fully illustrating the invention in accordance withthe requirements of the statute, and that such disclosures are not to beconsidered as amounting to limitations upon the scope of the invention,except as they may be specifically defined in the appended claims.

Having thus described my invention, I claim:

1. In an electrical control system, an operating circuit comprising athermostatic operating switch, adapted to be actuated by the applicationof heat, a heating coil for said switch, a first control thermostat incircuit with said coil, a second control thermostat, and electricalmeans controlled jointly by said first and second control thermostatsfor disabling said heating coil circuit and holding said switch intheactuated position.

2.` In an electrical control system, an operating circuit, an operatingswitch for controlling said circuit, said switch having a thermostaticelement adapted by the application of heat to move toward switchactuating position, a heating coil for said thermostatic element, afirst control thermostat in circuit `with said heating coil, a secondcontrol thermostat, electrical rmeans controlled jointly by said 'firstand` second control thermostats for disablin said coil circuit andholding said switch in t e actuated position, a safety switch adapted todisable said operating circuit, and means adapted to be set in motion bythe continued movement of said thermostatic element for actuatingsaidsafety switch in the event that said electrical means should fail tooperate.

3. In an electrical control system, an operating circuit, an operatingswitch for controlling said circuit, said switch having a thermostaticelement adapted by the application of heat to move toward switchactuating position, a heating coil for. said thermostatic element, afirst control thermostat in circuit with said heating coil, a secondcontrol thermostat, electrical means controlled jointly by said firstand second control thermostats for disabling Asaid coil circuit andholding said switch in the actuated position, a safety switch adapted todisable both of said circuits, and means adapted to be set in motion bythe continued movement of said thermostatic, element for actuating saidsafety switch in the event that said electrical means should fail tooperate.

4. In an electrical control system, an operating circuit, an operatingswitch for controlling said circuit, said switch having a thermostaticelement adapted by the application of heat to move toward `switchactuating position, a heating coil for said thermostatic element, afirst control thermostat in circuit with said heating coil, a secondcontrol thermostat, electrical means controlled jointly by said firstand second control thermostats for disabling said coil circuit andholding said switch in the actuated position, a safety switch adapted todisable both circuits, means adapted to be set in motion by thecontinued movement of said thermostatic element foractuating said safetyswitch in the event that said electrical means should fail to operate,said safety switch being returnable manually to the actuated position.

5. In an electrical control system, an operating switch, thermostaticmeans for actuating said switch, an electric heating coil for actuatingsaid thermostatic means, an electric circuit in which said coilislocated, a second switch for controlling said circuit and a relay havingan armature adapted when the relay is energized to actuate said secondswitch and hold said operating switch in actuated position.

6. In an electrical control system, an operating switch, thermostaticmeans for actuating said switch, an electric heating coil for actuatingsaid thermostatic means, an electric circuit in which said coil islocated, a second switch for controlling said circuit, a relay having anarmature adapted when energized to actuate said second switch hold saidoperating switch 1n actuated position, and a safety switch foltheoperating circuit, said safety switch being adaptedto 5 be actuated bythe continued' movement of said thermostatic means in the event that'said relay should fail to actuate said second switch.

7. In apparatus of the classdcribed, an 1 operating circuit, anoperating switch for controlling said circuit, a thermostatic elementadapted to actuate said switch, a relay having balanced coils connectedin parallel lines to one side of said operating switch, said relaycontrolling said operating circuit, and means ada ted to be set inmotion by said thermostatlc element for disabling one of said parallellines when said thermostatic element is operated beyond normal switch 9actuating-position.

8. In apparatus of the class described, an -operating circuit, anoperating switch for .controlling said circuit, a thermostatic elementadapted to actuate said switch, a relay 53 having balanced coilsconnected in parallel lines to one side of said operating switch, saidrelay controlling said operating circuit, means adapted to be set inmotion by 4said thermostatic element for disabling one of said parallellines when said thermostatic element is operated beyond normal ition,and thermostatic means also adap to disable one of said parallel lineswhen a given temperature is exceeded.

9. In an electrical control system, two thermostatic switches, both ofsaid thermostatic switches having contacts adapted to open undertemperatures exceeding predetermined heights, an operating circuit,arelay control- 4 ling said operating circuit and having balanced coilsconnected in parallel lines within said operating circuit, said twothermostatic switches being connected in multiple within one of `saidparallel lines, whereby said last named parallel line is disabledwhenever both of said thermostatic switches open their contacts. A

10. In an electrical control system, an operating circuit, an operatingswitch for said 5 circuit, a thermostatic element adapted when heated tothrow said switch to actuated position, a holding means for maintainingsaid switch in actuated position, an electric heating coil arrangedadjacent said thermostatic element, and a control circuit comprising 'arelay having an armature to which said holding means is connected.

In testimony whereof, I hereunto aix my signature.

ROBERT J. EISEMAN.

